Scale and pointer indicator



Sept. 17, 1940. v w ZUPANEC 2,215,310

SCALE AND POINTER INDICATOR Filed March 23. 1939 Fig. 3.

, Inventor: William Zupanec,

Hrs Attorney.

Patented Sept.1940 a t carried by the pointer.

UNITED STATES 1 PATENT OFFICE- V 2 31 1 I Q William Zupanec, Schenectady, N. Y., assignor to Genfiral-Electric Company, a corporation of New Yo'r Application March 23, 939. Serial m..- 263,685

' scams. -(Cl.88-1) My invention relates to indicating 'devlces if the observer-is to the left of a correct reading equipped with a scale and a pointer cooperating position, the reading willbe too high. This gives with the scale such as is employed in numerous rise to what is termed parallax and errors due measuring instruments and meters and'its obto parallax. It is the apparent different posi- --ject" is to increase the ease and accuracy of the tions'of the pointer with respect to the scale when' reading of such instruments and in particular observed from "difi er'ent points. It has hereto- 'to avoid that type of reading error known as the fore been. proposed to provide a mirror back of parallax error. A further object of my invention or in the plane of the scale for reflecting a is to provide an instrument scale andpolnter arportion of the pointer to assist the instrument m rangement that may be accurately. read from any reader in placing his eye in the correct reading m convenient observation angle. position-where there is no error due to parallax. In carrying my invention into eifect in its pre- This is accomplished .when the pointer and its ferred form, I provide a mirror midway between image are in line with theeye; This expedient,

- the pointer and scalein the path of vision so that o (1088 not p rmit of correct y reading the u in case the reading is made'from an angle, other instrument pointer position from any angle. It 5 in themirror will appear to line up with the'acinstrument may be'read correo lytual position of the pointer perpendicular to the According to my. invention the instrument scale. may be correctly read from. any position where p m The features of my invention which are bethe scale and pointer are clearly visible. For this golieved to be novel and patentable will be. pointed purp se I pr vi e a r r l1 midway between out in the claims appended hereto. For a better e pointer II and Scale Wand running h understanding of my invention reference is made length of th scale- This mirror y be Placed in the following description to the accompanying adjacent the lower edge of the scale or, as repredrawing in which Fig. 1 represents a face view 'sented, adjacent the middle of the scale. In any 25 of a scale and pointer arrangement embodying case the mirror is so placed along the scale that my invention; Fig. arepresents a side sectional th r fle ti th p t r t in m be view through the scale and mirror adjacent the pared to e Scale r i The m r y pointer; Fig.8 represents an enlarged view edge-. be a t p P l h d m l and Supported wise 'oi'the scaleand mirror inthe line of the p p r p i n w h r spect to the scale pla so pointer illustratingthe reflection reading princid p t r by ur t to t m d-s pie for various observation angles; Fi 4 e the scale plate by supporting structure indicated sents what is seen in th mirror when; reading at [3 in Fig. 2 so that the scale graduations exis taken at an angle; and Fig. 5 shows a. mirror find out from either edge thereof as shown in than perpendicular, the reflection of the pointer merely indicates theone -position from which the In Fig. 1; I have shown the face orjiront view By plac n such a irr r w y between of an ordinary scale'plate Ill provided with gradthe scale and pointer the reflection of the pointer 1 uations as shown and apolnber II in from; ofand in' the mirror,-- if it can be Seen at 8.11, will be in cooperating with th cal I th operation of line with the scale graduation directly beneath the instrument on which the scale and pointer he pointer-and this refl image of the pointer g.

are used the pointer. swings over the scale and will give a correct reading on the scale from all is some distance above the scale as represented angles. The reason for this is illustrated in Fig. in the sectional side view, Fig. 2. with the con- I person v st Pointer and a e ventionalarrangement as. thus far described'a m t p sit n f n pa a error, at i person desiring to accurately read the measurewith his eye in a plane perpendicular to the scale 5 ment position of the pointer with respect to the plate and in line with thepointer along line llscale must be careful to view the pointer and lI-li, vfor example in Fig. 3, the correct readscale from 'a point in a plane perpendicular to lng will beobtained and the reflection of the the scale and-in line with the pointer. pointer II in mirror. I! will not be seen. This If, now, it be assumed that the same pointer is the same procedure as for correctly reading 50 Y position beread but with the observer in an ininstruments of the prior art, and mirror l2 can accurate reading position, say to the right of the be used to aid the observer in thus positioning correct. reading position. the pointer will appear himself,-lt he so desires. For example, he mereto be down scale from the position represented ly places his eye in line with. the pointer and its 5 and the reading will be low. 'In the same way. reflected image when readin the instrument;

However, this is now no longer necessary. Let us suppose, for example, that the observer views the scale along the. line l6-l5, pointer ll remaining in the same position directly above scale 5 point I5. Since the mirror M is half-way between pointer H and scale plate ill, the observer sees the reflected imageoi pointer H at point I! 'of the mirror in line l6-li. Actually the reflected image appears to be at point l5. In other 10 words the reflected image of the pointer appears to be at the correct reading point I! of scale ill, and the instrument is correctly read by noting the position of the reflected image of the pointer on the scale. It the observer be at a diflerent l5 angle, for example looking along line l8-l5, the reflected image of the pointer appears at I! in line l8|5 and again a correct reading is obtained by observing the position of the reflection of pointer II on scale I 0. Thus correct readings 90 may be taken from any convenient angle and two or three persons may simultaneously read the instrument from different angles and all read it correctly.

It is assumed, of course, that a person who 26 thus reads the instrument from an angle understands that he must look at the reflected image of the pointer in mirror l2 instead of looking at the pointer itself. This is not difllcult since the reflection of only a part of the pointer appears in the mirror at only the proper position and if the pointer is of substantial width, I may provide a reference reading line on its back surface.

The pointer side nearest the observer possibly a may also be reflected in the mirror but by making the pointer thin at this point or by making the side and rear surfaces of contrast n appearance, as by making the sides black or dull and the rear white or polished, no difliculty is experienced in clear visibility of the reflected dllmage of the rear surface of the pointer. Thus in Fig. 4, ll may represent the reflected image of the pointer as seen inmirror l2 against scale plate I0, the line Zli representing the reflected image of a reading reference line drawn through I the center of the rear surface of the pointer.

The important precaution to be observed in utilizing this invention is to have the mirror surface equally distant from the front surface of the scale plate and the rear surface of the pointer 50 for all pointer positions along the scale. A thin strip of metal mirror may be readily added to most existing instruments fer the purpose of utilizing this invention. If supported by the scale plate, it should run the lengthof the scale. The mirror may, however, be carried by the pointer, in which case a relatively short, light-weight mirror may be used as shown at 23 in Fig. 5. In such cases themirror supporting clip 24 should be suitably spaced from the observation area closely about the pointer end. In Fig. 5 the reflected image'of the pointer 22 is indicated at 22'.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only 1 illustrative and that the invention may be car- 5 ried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

2 1. In combination, a graduated scale, a pointer movable over said scale andindicating thereon, said pointer being spaced from said scale, and mirror means for producing an image of the rear side of said pointer appearing in the plane of the scale at a point on said scale directly opposite said pointer when such scale point is observed 25 from a point to one side of said pointer, said mirror means being supported parallel with the scale and half-way between it and the pointer and being so dimensioned that the scale graduations are visible along the edge thereof. G

2. In combination, a graduated scale plate having a pointer movable over said scale for indieating thereon, said pointer beingspaced from said scale, and a mirror narrower than the scale and extending from end to end or said scale and supported from said plate ln a plane equally distant from thescale and pointer for the purpose of producing an image of said pointer in correct reading position on said scale when readings are taken from positions other than from in a plane 49 perpendicular to said scale and in line with said pointer. v

3. In combination, a graduated scale, an indicator spaced from said scale and movable over said scale in a; path parallel to said scale, and a mirror narrower than the scale so that the scale graduations extend out from the edge of the mirror, said mirror being carried by said indicator in a plane parallel to said scale and midway between said scale and pointer for the purpose 50 of reflecting a scalereading image of said pointer.

WILLIAM ZUPANEC. 

